Lecture 5 – Covalent Compounds: Macromolecules

ACKNOWLEDGEMENT:

Figure	Source of Figure
Figure 17	www.chemguide.co.uk

Macro Molecular Bonding:

The other type of covalent bonding is Macro Molecular bonding. Macromolecules like simple covalent molecules are formed by electron sharing in non-metals.

Figure 17:

Figure 17 shows the macromolecule of sand, SiO₂. SiO₂ molecules form giant covalent molecules, often forming tetrahedral structures with large intermolecular forces of attraction. These large intermolecular forces give the macromolecules their high densities, melting and boiling points.

All the valence electrons are shared, therefore neither ions nor electrons are present to allow the passage of electricity, due to which macromolecules, like simple covalent molecules, are non-conductor of electricity.

Table 8: Properties of Macro Molecular-Compounds

Property	Reason
High melting and Boiling points	Strong forces of attraction between the shared electrons and tetrahedral structures require large amounts of heat to melt
Non-Conductors of electricity	Covalent compounds are non-conductors of electricity in any state as the electrons shared CANNOT move, and neither ions nor free electrons are present to carry the electric current